Looks like limestone to me also. Have lots of it in are area.

J.Carlson

You may be able to strike it with a piece of steel and get sparks. 

The better quality stuff was used to make arrow heads and other tools by the ancients.

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Looks like common limestone.

If it's flint/chert it will break and feel like oily glass.

You could sell flint/chert online. I paid a mint for some recently (long hobby since a kid).

This is a great channel. He has a video on finding rocks to start with.

https://m.youtube.com/@DonnyDustsPaleoTracks" rel="nofollow - https://m.youtube.com/@DonnyDustsPaleoTracks

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The first picture is your rock, the other two are mine. I think you can see some similarity although the dark portion on mine appears smoother. 

On mine the dark part is very hard and very smooth yet similar in color to yours. 

The Chert/Flint is sort of encapsulated in the softer brown material.

When my brother and I ran across these when we were kids we called them dinosaur bones because the brown part sorta has the texture and color of old bones. 

As I said, a few years ago I found a "vein" of this stuff after a flood washed out one of my old log roads.

Rocks are formed as a result of materials being compressed together, and chemically binding from any number of circumstances.

There's three basic types of rocks:

Sedimentary, Igneous, Metamorphic

Sedimentary are just as they sound- the result of water and wind distributing surface accumulation of material, then pressure and chemistry binding the soil contents together.  The indicator of a sedimentary rock, is layeriing, and the general ease at which it can be broken into layers and dust.  Limestone and sandstone are the most common examples, formed from clay.  Chirt is a type of limestone where biological organisms's decay leaves behind exoskeletal remains that form a high content of particular patterns of metals like calcium, phosphorus, pottasium, silica, iron....

Igneious rocks are magmatic- formed by intense heat and pressure... and usually when this happens, there's lots of things that simply don't appear because, at that temp and pressure, the other stuff simply cannot stick around... it gets 'boiled out.  Igneous includes more iron and silica... with smaller components of sedimentary source to form basalt, granite, mica and quartz, flint, feldspar...  and if it happens to be infused with gasses that expand as it freezes, it'll form abrasive crystalline structures like pumice, ash, and stuff.

Metamorphic is what you get when sedimentary rock is subjected to high enough pressure and temperature to melt, but not flow.  It gets patterns and layers, but it doesn't easily break apart, because it has interfused itself.   Slate, marble and quartzite are the metamorphics most people come across regularly.

Don't know what they could be.

My property is in a limestone area, but several bits of sandstone pushed up into the limestone. I have been told more soil types in my county than most midwestern states.